Mixing apparatus



April 10, 1928.

A. P. GRUNN MIXING APPARATUS Filed March 1927 Patented Apr. 10, 1928.

nairan states ALBERT r; GBUNN, or CHICAGO, ILLINOIS.

' meant MIXING APPARATUS;

Application filed March 15, 1927, Serial No. 175,498.

The object of the mixing apparatus described and claimed herein is to provide means for the thorough andrapid admixture of the investment compound with which wax dental patterns are painted in the preparation of the moldsfromwhich the castings are made.

of the casting The perfection of form depends upon the formation of a perfectly homogeneous mixture of the investment compound with water and the complete elimination of airbubbles' therefrom. The use of an imperfectlymixed investment compound or the presence of air bubbles therein causes irregularlties in the form of the castlng, and as in this class of Work the utmost precision of form is n'eces sary the process of mixing assumes animportance and difficulty not present in work 1 requiring less precision. Exclusion of bubbles and thorough admixture are difficult '7 and not always attainable When hand spatulation is depended on. In myattempts to construct a mechanical mixer I have found that without the provision of means especially adapted to the purpose satisfactory results cannot be accomplished, and it is to the means devised for thispurpose that this ap plicationfor patent is directed.

In the drawings: Figure 1 is a perspective view of the complete structure, the hand piece of a dental engine and the hands of the operator being shown in dotted lines. 7

Figure 2 is a central longitudinal section through the mixer shown in Figure 1.

Figure 3 is a section on the line 3-3 of Figure 2. c Figure 4 is a section onthe line it-4 of outwardly projecting boss, 9, through which extends an elongated bearing aperture, f. The mixing or spatulation is effected by a rotary spatula comprising a shaft, h, with blades projecting radially therefrom; In

spaces between the side of the'shaft;

inating the possibility of rial escaping thorough spatulation. ,1

each side of the shaft of the axis of the shaft and theuppermost blades adjacent the cover, asoppositely 'into be clutched, will from-diametrically opblades upon each side being oppositewthe rangement of the blades the material passing between the blades ters the blades of the other-series thus elim- EFFECEr j of one series encouni of thefmatethe-structure illustrated the are in two series projecting posite sides of the shaft, the intermediate 1 60 blades onthe opposite By this "staggered ar-r:

- I have shown the threelower blades'upon i I as flying in the plane clined to the plane of the axisof the shaft whereby rotation of the shaft in the" direc-- tion of rotation of the shaft of the dental mixer shaft is designed force the material in the mixer toward the closed end thereof and away from the cover andthe-bearing aperengine, to which the blades upon each side of the shaft-in the plane of the axis of the shaft facilitatesthe' ture therein. The position of thelower three so i escape from the investment mixtureof-air bubbles which have inclined blades. vision of two inclined blades adjacent the cover is sufficient to provide circulation of the mixture andto keep it away from the cover and from the shaft bearing therein.

a tendency to adhere to I havefound that the pro- I V The bearing aperture, 7', in, the cover is counter-sunk at its inner end as shown atz' to'form a seat for a projecting annular shoulder, is, formed on the shaft, h. The

bearing surfaces of the shoulder, k. and

shown-as 'spherlcal 1n counter-sink z are form, thereby permitting some variation in the angular position of theshaftwithout destroying contact faces referred to. The distance, frorn the shoulder is to the inner-end of the shaft is slightly less than the distance from the bearlng surface of the counter-sink i onlthe cover to the inner end of the cylindrical vessel when the cover is in position as-shown in Flgure 2, thereby permitting some clearance between the inner end of the rotary spatula and the closed end of the vessel. As above stated, the inclination of the upper blades, Z, m, forces the material in the mixer toward the closed end andaway from the cover, and

the reaction upon the rotary spatula blades, Z, m, impels the rotary spatula toward the between the bearing surcover thereby establishing close sealing con v shoulder lc-and counter-sink vi and at the apparatus are 7 toreadily clean allparts of f each time itis used.

, .dricalves'sel open atone end,

'sametime establishing working clearance be tween the inner end of the rotary spatula and the closed end of the cylindrical vessel a,

' As shown in Figure 1, the outer.proj ecting to the shaft in'the hand piece of the dental engine indicated at 0. In operation the op-l BI'atOfl'lOIldSfthB- hand piece with one hand 'andthevess el cp'with the otherhand. "The elongated bearing f and counter-sink bearing 2' dispense with the necessity of any bearing a t'the inner endof the rotary spatula'.-and the fact that the three parts of the separable released from the mechanism I claime I l In a device of the classdescribed, a cylinsaid open end, ing the cover extending through and projecting end of the shaft is designed to be clutched :When the cover is the vessel makes. it possible a cover for V means for detachably securto the vessel,'the cover being provided with a central bearing aperture, a

dial blades projecting beyond said bearingaperture andhaving thereon an annular shouller of greater diameter than the aperture and adapted to bear against the inner side of the cover thereby restrainingtlie spatula against outward movement but permitting the spatula and cover to be separated, blades on oppositesides of said rotary spatula comprising a shaft and ra- V therefrom, said shaft s shaft being oppositely inclined whereby 'ro- V tation ofsaid spatula inone direction forces said shoulder against the inner side of said cover thereby sealing saidyessel during ro- ,tation of said'spatula.

In testimony whereof, I have subscribed my name.

ALBERT RGRUNN; I 5, 1 

